This invention relates generally to a system and method for enhancing hearing in patients suffering from sensorineural hearing deficiencies and more particularly to a system including a middle ear implant for handling lower frequency sounds and a cochlear implant for handling higher frequency sounds.
Hearing loss is frequently categorized as being either xe2x80x9cconductive hearing lossxe2x80x9d or xe2x80x9csensorineural hearing lossxe2x80x9d. Conductive hearing loss typically refers to middle ear impairment and generally results from damage to the tympanic membrane and/or middle ear ossicles. Sensorineural hearing loss is frequently attributable to a reduction in function of hair cells within the cochlea. When sufficiently severe, sensorineural hearing loss can be mitigated by implanting electrodes in the cochlea to electrically stimulate the auditory nerve. When less severe, hearing loss can be mitigated by enhanced activation of the middle ear mechanism. For example, the prior art describes various electrically driven actuator devices for physically contacting and mechanically vibrating the middle ear ossicles.
Great strides have been made in the development of cochlear implant systems for restoring hearing in people suffering from severe sensorineural hearing loss. Such systems are typically comprised of an implant housing containing implant electronics for driving an array of electrodes which are surgically inserted into the cochlea. The implant electronics is typically driven by sound processing electronic circuitry which is generally, but not necessarily, contained in a housing worn externally by the patient. A microphone carried by the patient supplies electric signals to the input of the sound processing circuitry. Typical sound processing circuitry and implant electronics provide for multiple frequency channels.
In order to provide for good speech comprehension, reception of sound across a broad frequency range from about 100 to about 16000 Hz is desirable. Mechanical stimulators such as conventional hearing aids and middle ear implants carry sound with high fidelity up to around 4000 Hz. The basal end of the cochlea is primarily sensitive to higher frequency stimulation and is well suited for handling sound above 4000 Hz.
The present invention is directed to a system for enhancing hearing comprised of both a middle ear implant and a cochlear implant. The system directs signals relating to lower frequency sound to the middle ear implant and signals relating to higher frequency sound to the cochlear implant.
In accordance with the preferred embodiment, the middle ear implant comprises an electrically driven actuator, e.g., a speaker for vibrating the middle ear ossicles via air conducted sound energy or a mechanical transducer for physically contacting and mechanically vibrating the ossicles.
A preferred cochlear implant includes electrodes implanted at a shallow level at the basal end of the cochlea.